Improve this diagram

http://www.andydoro.com/table/images/circuit.gif


There are four coils that sense EMF and light up some LEDs accordingly. However from some comments I have read, whoever made this has made some errors. So far here is what I have spotted:

1. No current limiting resistor for LED
2. R4 is wasting power, it should be removed

Anything else? Thanks!

That schematic is so bad even I can't believe it.

It looks like he started out with a circuit designed for an LM339 comparator (which has open-collector outputs, thus requires a pull-up resistor on the outputs) and slapped in an LM324, which doesn't require pull-up resistors.

The feedback resistors are so large in value they may as well not be there.

The noninverting inputs are set to +V/2 by R1/R5 so unless the inputs exceed that, the outputs will never go high.

As you mentioned, the LEDs need current limiting resistors.

The schematic is so poorly drawn that it detracts from a good analysis of what the original intent was.

I think you called the key mistake, he substituted a LM339 with a LM324. If that were the chip used then the pullup resistors would be the current limiting resistors for the LEDs, and valid.

OK, so it looks like I am better off making a circuit from scratch.

I am thinking about this, the coil is put on the input of a divided feedback circuit, and that boosts the voltage to a higher level (5v?), and that voltage is put through a voltage to current circuit, which lights up an LED accordingly. Does that sound feasible? Thanks!